1. Field of the Invention
The invention concerns a mount for aircraft engines, in particular for turbofan jet engines. On the pathway of the airstream passing through it, from upstream to downstream, an engine comprises an air inlet, a fan case, an intermediate case, a thrust mount, an exhaust case and an exhaust nozzle.
2. Description of the Related Art
An engine is generally attached to the aircraft by a forward mount and an aft mount. But there may be more than two mounts. The forward mount is attached to the intermediate case of the engine, and the aft mount onto a mounting ring connected to the exhaust case by a series of links and to the intermediate case via reverse thrust means when mounted onto the rear of the fuselage.
When the engine is mounted under the aircraft wing, the thrust mount comprises a plurality of thrust links. When the engine is attached to the fuselage, generally at the rear, the reverse thrust transmission between the reverser and the intermediate case is made via an outer fan duct. The invention especially, but not exclusively, concerns engines with an outer fan duct and the forward mounting of these engines. It also more particularly concerns the failsafe system of this mount, in which an engine is connected to a beam which itself is attached to an element of the aircraft frame, generally a pylon.
The intermediate case is attached to the beam of the forward mount at three points, respectively at the two side ends which are generally the high and low ends of the beam, and at a median part via three load transmission elements. The end elements of the beam are links, and the element of the median part is a central spigot.
The forward mount of an engine attached to the side of the rear fuselage ensures load transmission in four degrees: three degrees in translation—vertical axis Z, lateral axis Y and following thrust axis X—and one degree of rotation about the thrust axis X.
In the event of failure of one of the mounting elements, it is desirable for the failsafe system to continue transmitting the loads along the degree associated with the failed element.
Failsafe means are already well known.
Document U.S. Pat. No. 5,474,258 describes means which consist of doubling the normal load transmission equipment, with the drawback of the complexity and weight of doubling.
Document FR 2 820 402 also proposes doubling the normal equipment with an emergency equipment.
In document FR 2 799 432 the applicant proposed a simpler and especially a more lightweight failsafe system. This document describes a forward mount for an aircraft engine with outer fan duct intended, via an intermediate case, to be attached to the rear of an aircraft fuselage, the mount being arranged to be attached firstly by a beam to the aircraft fuselage, and secondly by two lateral and a median load transmission element to the intermediate case of the engine, the mount comprising an integrated load transmission and failsafe assembly arranged to ensure the continuity of load transmission in the event of failure of a load transmission element and to perform its failsafe function in unitary, concentrated fashion in the median zone of the mount.
With said mount, all the loads intended to be transmitted by a given element of the mount, after failure of such element, continue to be transmitted by the unitary failsafe means.
However, in this prior art it is provided that the loads intended to be transmitted by the lateral thrust links, in the event of failure, are transmitted by the central spigot. In another embodiment, provision is made for the loads of the thrust links, in the event of failure, to be transmitted by a sleeve flange.